1. Field of the invention
The present invention relates to a photosensitive resin composition having a sensitivity to light of a long wavelength, of a laser such as a helium-neon laser or a semiconductor laser, and a method of preparing a volume type phase hologram member using the composition.
2. Related Background Art
Diligent research efforts and progress have recently been made on photosensitive materials used for laser beam writing, both in the field of image recording techniques of digital systems and in the field of holography.
In particular, there are strong demands for photosensitive resins or photosensitive materials having a sensitivity to long-wavelength light of helium-neon lasers, semiconductor lasers, etc. that ranges from the visible region to the near infrared region.
To satisfy such demands, a proposal has hither to been made in Japanese Patent Application Laid-open No. 62-215284 for a photosensitive material for hologram recording and designed to have a sensitivity to long-wavelength laser light. Disclosed in the Japanese Patent Application is a photosensitive material comprising a carbazole ring-containing polymer as a chief agent and a triphenylmethane-type dye contained as a photoreaction initiator.
Such a photosensitive material, however, has had the problem that the triphenylmethane type dye is dissolved in an organic solvent only with difficulty. In particular, the dye has such poor solubility in an aromatic solvent that removal of the dye after exposure to laser light can only be accomplished with difficulty.
Such a photosensitive material has also had the problem that it has no sensitivity to the light of semiconductor lasers, which light is longer in wavelength than the light of helium-neon lasers.